Hormesis

Hormesis is a biological phenomenon where a beneficial effect (improved health, stress tolerance, growth or longevity) results from exposure to low doses of an agent that is otherwise toxic or lethal when given at higher doses.

Definition

Hormesis is characterized by dose-response relationships displaying low-dose stimulation and high-dose inhibition. Hormesis is observed also in the responses of many animals to certain levels of all types of stressors. The hormesis model of dose-response is vigorously debated. The biological mechanisms by which this occurs are not well understood, although a number of theories have been proposed.

History

The term "hormesis" comes from the Greek word hormo, which means "to excite". It was first used in the scientific literature in 1943 by Southam and Ehrlich.

Mechanisms

The mechanisms of hormesis are varied and can involve a multitude of pathways. Some of the proposed mechanisms include the upregulation of protective enzymes and stress response genes, the activation of immune responses, and the increased production of antioxidants.

Applications

Hormesis has potential applications in many areas such as toxicology, risk assessment, radiation protection, aging research, and medicine.

See also

• Toxicology
• Radiation protection
• Aging research
• Medicine

References

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